Jitter is the time variation of a periodic signal in electronics and telecommunications, often in relation to a reference clock source. Jitter may be observed in characteristics such as the frequency of successive pulses, the signal amplitude, or phase of periodic signals. Jitter is a significant, and usually undesired, factor in the design of almost all communications links. Jitter in magnetic media often constitutes the dominant source of signal noise. On average, jitter contributes eighty percent (80%) of signal noise, versus twenty percent (20%) of AWG (additive white Gaussian) noise, in modern perpendicular recording media.
Data transitions can contribute to the presence of jitter in a communication signal. In a sequence of data bits, a change from a one to a zero, or from a zero to one, represents a transition. As data transitions increase in a communication signal, a corresponding increase in jitter can be seen. As a result, as transition density in a communication channel increases, the signal-to-noise ratio (SNR) of the signal decreases.
There is, therefore, a need in the art for improved high-rate transition control code for reducing jitter noise in magnetic recording channels.